The present invention is in the field of conformal thermal sensing and imaging. Conformal temperature sensing has applications in a number of fields. Conformal sensing of various physical parameters is ongoing. A number of researchers have used micromachining techniques to develop sensitive skin sensors for robotics. Flexible multimodal polymer sensor arrays have been realized as well as shear sensor arrays with embedded silicon elements. Even though these devices are able to achieve some degree of conformability, the conformability is restricted to simple curvatures like a cylinder. They cannot stretch or conform to accommodate three-dimensional objects like a sphere, and thus fail to fulfill their roles as “skins”. Other researchers have explored embedding wires and sensors in traditional textile fabrics to yield “smart fabrics” capable of sensing biometrics of the wearer. The present invention uses a combination of these approaches to create micromachined fabrics with embedded temperature sensors that have good conformability to three-dimensional objects.
The decoding of localized thermal input has been utilized to detect the defects in circuits of both discrete and integrated electronic components. This does not only apply to thermal sensing, but also more generally to when a localized input is acquired over a relatively sensing area, and usually involves large number of sensor arrays, cumbersome wiring and complicated test setup. The present invention comprises sensing and processing schemes that can greatly reduce the number of sensors required and associated testing complexity. In addition, the present invention facilitates conformal imaging by embedding the temperature sensors in micromachined fabrics.
Advances in integrated circuits, semiconductor materials, and micro-machining techniques are being combined in interesting ways with everyday items in an effort to reduce their obtrusiveness. This includes efforts to develop wearable computers, cell phones, medical diagnostic sensors, and so forth. A key segment of this work is the development of what can be termed “smart fabrics”. Smart fabrics can take many forms, but in general represent textiles that perform a specific engineered task such as routing wires, sensing, providing power (e.g., solar cells), serving as an actuator or serving as an antenna while functioning as a mechanical component of an item of clothing. Examples of work in this area include development of strain and temperature sensitive fabrics for injury rehabilitation, fabric-based antennas and inductors for wireless communication and networking, CMOS-based flexible pressure sensitive fabrics, bio-monitoring fabric, and a number of efforts to develop fabrics that can serve as circuit boards for wearable computing. The present invention has uses in any one or more of these areas, for example.
Temperature monitoring devices have been disclosed. For example U.S. Pat. No. 6,152,597 is directed to a conformable device for temperature monitoring of a power source and U.S. Pat. No. 6,814,706 to a skin patch for temperature sensing. Those devices, however, are rather limited in their ability to sense spatial thermal distribution over a surface, including a planar, non-planar or bent surface. U.S. Pat. No. 6,180,867 discloses a surface conformable thermal sensor array for diagnosing breast cancer. That sensor, however, requires a large number of thermal sensors and associated wiring in order to obtain an accurate thermal image. Similarly, U.S. Pat. No. 6,034,374 is configured so that the image requires a large number of individual thermal sensors. Previously disclosed temperature sensors generally suffer the drawback of requiring an excessive number of thermal sensing elements to adequately resolve a thermal image. Further, many conventional temperature sensors lack the mechanical conformability required to provide accurate measurement of temperature distributions of non-planar (e.g., curved) surfaces. The present invention overcomes these limitations by selectively orienting thermal resistor wires within separate conformable polymer layers.